Ben Hope and Jason Richards displayed no emotion as the verdict was read out at Swansea Crown Court. Both were found guilty of murdering 17-year-old Aamir Siddiqi and attempting to murder his parents when they intervened. Aamir's family let out a small whoop of joy as the guilty verdicts were read out.

Hope and Richards will be jailed for life at the same court next Friday when judge Mr Justice Royce will set the "substantial" minimum term they will serve.

The attack, which happened when the men went to the wrong address, took place on a quiet Sunday afternoon in Roath, Cardiff, South Wales, in April 2010.

Balaclava-clad Hope, 39, and Richards, 38, both from Cardiff, were each paid £1,000 in "blood money" to murder a middle-aged family man, who owed money to a shady businessman. But the hitmen murdered the teenager instead when they visited the wrong address. The intended target escaped with his life as a result.

"I think that they have done something very sinister," Mr Siddiqi said. "Since these verdicts we feel that justice has been done. We do not want revenge, or to feel bad towards anybody, but when someone has done something so bad they should be punished."

Mr Siddiqi added: "With his departure life has become very empty and somewhat meaningless. Aamir was everything in my life."

His wife Parveen Siddiqi said: "Aamir was a boy that everybody thought well of. He was bright and polite. The day Aamir was murdered he had just asked if I wanted tea."

Umbareen Siddiqi, 33, the teenager's sister, paid tribute to her brother outside court, describing the attack on him as "callous and vicious". She said: "Today's guilty verdict is the right one and as a family we are both delighted and relieved."